Journal of Clinical Psychopharmacology
Volume 20(2), April 2000, pp 272-273
Naturalistic Study of the Weight Effects of Amitriptyline, Fluoxetine, and
Sertraline in an Outpatient Medical Setting
[Letters To The Editors]
Sansone, Randy A. MD; Wiederman, Michael W. PhD; & Shrader, John A. MD
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With the possible exception of protriptyline,1 a clinical concern with the
administration of tricyclic antidepressants has been weight gain.2, 3 In
contrast, the prescription of selective serotonin reuptake inhibitors (SSRIs)
may result in either weight loss 4-7 or weight gain.8-12 Most studies exploring
appetite or weight effects with SSRIs have been short term (i.e., days to
weeks). However, time effects may be important, because weight loss with
fluoxetine may occur at the beginning of treatment, but may not continue to a
meaningful degree.7, 13 This study was undertaken to retrospectively explore in
an ambulatory clinic the naturalistic weight effects over a several-month period
of treatment with amitriptyline, fluoxetine, and sertraline.
Methods
In an ambulatory internal medicine clinic, all patients receiving amitriptyline,
fluoxetine, or sertraline, the most commonly prescribed antidepressants in this
practice setting, were identified using a computerized office practice
management system.14 Only those patients with a recorded weight at antidepressant
initiation (seen from July 1, 1984, through October 14, 1997) were selected for
the study. Data reviewed included age, sex, weight, and antidepressant type,
duration, and dose. The most recent weight in the electronic record during the
period in which subjects were being prescribed the antidepressant, as well as
the number of months between the drug-initiation weight (time 1) and the last
weight (time 2), were coded (less than 1 month was coded as 0). Weight change
was calculated by subtracting the weight at time 1 (drug initiation) from the
weight at time 2 (i.e., positive values represent weight gain, whereas negative
values represent weight loss). When varying doses of antidepressant were
prescribed over the study period, the highest dose was coded. Because of the
retrospective nature of this study, it was not possible to control for several
variables that might have influenced body weight in individual cases (e.g.,
prescribed weight loss, or weight changes resulting from mood disorder, severity
of psychopathology, medical conditions, and adjunctive medications).
Results
The final sample consisted of 544 patients. The descriptive data are presented
in Table 1 as a function of the prescribed antidepressant. Amitriptyline was the
most commonly prescribed antidepressant (N = 284), followed by sertraline (N =
180) and fluoxetine (N = 80). Equal proportions of patients in each antidepressant
group were female. Patients in each category did not differ with regard to mean
age or mean weight change. However, post hoc Scheffe tests revealed that, with
regard to starting weight, patients prescribed amitriptyline weighed significantly
less than did patients prescribed fluoxetine. With regard to the mean number of
months receiving antidepressant treatment, patients prescribed amitriptyline
continued treatment for a greater length of time compared with patients
prescribed sertraline. Doses most prescribed were 25 mg (47.4%) or 50 mg (31.3%)
of amitriptyline; 20 mg (77.5%) of fluoxetine; or 50 mg (73.1%) or 100 mg
(20.6%) of sertraline.
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Table 1. Descriptive data as a function of antidepressant treatment (N = 544)
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The three study cells did not differ with regard to mean weight gained or lost
during the study period. However, we calculated the proportion in each group
that evidenced some degree of weight gain, which was identical for amitriptyline
and fluoxetine groups (52.5%) and significantly higher than for the sertraline
group (40.0%) ([chi]2 [2, N = 544] = 7.50, p r = 0.01), fluoxetine (r = 0.13),
and sertraline (r = -0.09). When considering only those patients who gained
weight during their course of treatment (N = 263), there were no differences
between the three antidepressants with regard to the number of pounds gained,
body weight at the start of treatment, age at start of treatment, number of
months on treatment, or proportion of patients who were female.
Discussion
The mean weight change while receiving antidepressant treatment was minimal and
did not differ as a function of antidepressant type. The proportion of patients
who gained weight was significantly higher among patients given amitriptyline
and fluoxetine compared with those given sertraline. For those who gained
weight, the amount was not significantly different among the antidepressant
groups and was not related to dosage.
Several important limitations must be noted for this study. First, this study
was retrospective in nature (e.g., some potential candidates had to be
eliminated at the outset because there was no body weight recorded at the
initiation of antidepressant treatment). Second, there are a variety of
potentially confounding variables relating to medical conditions and the
prescription of other medications that may have influenced weight changes in
this sample. Third, there were several differences between study groups (e.g.,
antidepressant doses were not comparable among study groups; the fluoxetine
group was heavier in terms of initial mean weight, perhaps related to anticipation
of weight-loss effects; the amitriptyline group had a longer mean duration of
treatment, possibly related to treatment of chronic disorders such as fibromyalgia).
Finally, the mean age of participants was approximately 50 years, and therefore
the findings may not be applicable to younger or geriatric age groups.
With each antidepressant type, some patients lost weight, others maintained
their weight, and still others gained weight, with no significant overall mean
weight change between groups. These observations mask a great degree of
variation across patients. Further research is needed to understand why
particular individuals gain weight while others maintain or lose weight when
taking antidepressants.
Randy A. Sansone, MD
Department of Psychiatry; Wright State University School of Medicine and
Kettering Medical Center; Dayton, OH
Michael W. Wiederman, PhD
Department of Psychological Sciences; Ball State University; Muncie, IN
John A. Shrader, MD
Internal Medicine Program and the Transitional Year Program; Kettering Medical
Center; Department of Medicine; Wright State University School of Medicine;
Dayton, OH
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